Carbon deposition mechanism and structural changes for zeolite-templated carbons

How do zeolite-templated carbons grow?

“…Complete filling of the micropores is achieved at 150 min (extrapolated value), indicating progressive development of carbon species during the first hour of synthesis. The reduction of the micropore filling rate thereafter might be related to diffusion constraints of ethylene within the micropore systems, as previously insinuated by Liu et al [16]. Similar can be deduced from the NLDFT pore size distribution, which is centered at 6.4 Å during the first 60 minutes of synthesis (Figure 1c), indicating that microporosity is homogeneously filled during the first hour.…”

“…The carbon materials further present a scant amount of oxygen with an overall C/O ratio of 12 to 13 (Figure 14a). The presence of oxygen was previously ascribed either as resulting from the reaction of the forming carbon network with the oxygen atoms of the zeolite framework [16], or more often from the zeolite dissolution process [56]. In the 13 C NMR spectrum of the carbon, a further contribution at 180 ppm is indeed distinguishable, which can be ascribed to carbonyl or carboxylic groups and demonstrates the incorporation of oxygen into the network during the zeolite dissolution treatment.…”

“…Despite the growing interest in ZTC science, rather little is known about their formation mechanism and on the key steps that govern their synthesis. Only few reports have been published that attempt at describing in detail the formation mechanism of ZTCs using zeolite X (FAU structure) as template [16,17]. Liu et al [16] recently reported an in situ mass spectroscopy observation of ethylene decomposition products, mainly H 2 , CH 4 and C 6 H 6 , during the development of ZTCs in zeolite X at 600 °C.…”

“…Only few reports have been published that attempt at describing in detail the formation mechanism of ZTCs using zeolite X (FAU structure) as template [16,17]. Liu et al [16] recently reported an in situ mass spectroscopy observation of ethylene decomposition products, mainly H 2 , CH 4 and C 6 H 6 , during the development of ZTCs in zeolite X at 600 °C. Based on in situ thermogravimetric analysis (TGA) the authors further claimed to identify three stages of the process: (i) an initial fast stage, in which carbon deposition is high, (ii) an intermediate stage in which carbon deposition is slower due to increased mass transfer resistance of ethylene, and (iii) a final slow stage in which carbon uptake is very weak.…”

On-Line Thermally Induced Evolved Gas Analysis: An Update—Part 1: EGA-MS

“…A thermogravimetric analyzer connected to a mass spectrometer (TG-MS) characterized the in situ mass change that a zeolite particle underwent during the thermoanalytical run, while the MS monitored the decrease in C 2 H 2 concentration and the appearance of C 2 H 2 decomposition products (H 2 , CH 4 , C 6 H 6 ) [ 190 ].…”